MISSOULA — The forecast for the northern Rockies this weekend remains active with widespread snow expected. Below is a break down of the expected timeline and impacts as of Friday morning.
Friday: Snow will develop in northwest Montana Friday afternoon and evening. Winter Storm Warning and Winter Weather Advisories are in place for areas across western Montana.
Winter Storm Warning:
Kootenai/Cabinet Region (3 pm Friday - 3 pm Saturday) Snow of 4"-to-10" possible. The highest totals are expected near the Idaho border along Highway 56 Bull Lake Road, Highway 2 from Troy to the Idaho border and in the vicinity of Yaak. Other valleys will see 2 to 5 inches.
Lower Clark Fork Region (Friday afternoon - Saturday afternoon) Mountains of 14"-to-18", valleys 4"-to-10" possible. The highest valley accumulations are expected near the Idaho border along Highway 200 from Thompson Falls to Heron and along Interstate 90 from Saint Regis to Lookout Pass. Locations further east can expect 2 to 5 inches.
Winter Weather Advisory:
West Glacier Region (5 pm Friday - 5 am Sunday): Mountains 5-10", Valleys 3-6" locations include Bad Rock Canyon, Essex, Highway 83 Bigfork to Swan Lake, Marias Pass, Polebridge.
Potomac/Seeley Lake Region (5 pm Friday - 5 am Sunday): Mountains 5-10", Valleys 3-6" locations include Highway 200 Bonner to Greenough, Highway 83 Seeley Lake to Condon, and I-90 East Missoula to Bearmouth.
Flathead/Mission Valleys (5 pm Friday - 9 am Saturday): Flathead Valley: 2-4", Mission Valley: Trace - 2" locations include
Bitterrrot/Sapphire Mountains (5 pm Friday - 3 pm Saturday): Snow 6-12" locations include Lolo and Lost Trail Passes.
The valleys of west-central and southwest Montana will remain dry Friday with light snow developing tonight into Saturday. Even though advisories are not issued, light snow accumulations of an inch or two will be possible.
Saturday: Snow will be most widespread and consistent for locations along the Montana/Idaho border. For the rest of western Montana light snow will fall through out the day with a few inches of snow accumulation expected. High temperatures will be in the low to middle 30's Saturday.
Sunday: Light snow showers will continue to fall adding to snow accumulations for all elevations through the day Sunday. Then Sunday night, the arctic front approaches. As it does, a system will bring another round of moderate to heavy snow across western Montana. Snow accumulations are still uncertain, however, most recent model runs show the potential for snow amounts of 3"-to-8" across western Montana Sunday night into Monday morning for valley locations with the heaviest snow falling in northwest Montana.
Monday: Arctic air is expected to impact northwest Montana. As is it moves through gusty winds could create very difficult driving conditions for the Monday morning commute. Blizzard conditions are still possible for northwest Montana from the Flathead Valley east to the divide Monday due to blowing snow and reduced visibility. As the front moves through, temperatures will drop into the singe digits and teens for highs in northwest Montana. West-central and southwest Montana will see temperatures in the 20's with light snow remaining in the forecast.
Tuesday-Wednesday: Confidence remains high on the arctic air moving into western Montana, however, just how far south and just how cold temperatures will fall still remains uncertain as models are still struggling to come into agreement. The highest confidence for bitter cold is in northwest Montana where highs will only be in the single digits. How far south the coldest air can travel still remains to be seen. As of now, the forecast for Missoula is to keep high temperatures in the teens Tuesday and Wednesday while Hamilton sees temperatures remain in the upper teens to low 20's.
Again, there is a lot going on with this forecast and many things could change through the weekend. We will continue to monitor and bring all the updates as they become available.